Countersunk Bolts

Countersunk bolts are often used to get a smooth surface. These bolts find their usage in projects such as railing, walkways, and bridge decking.

Manufacturing

BBI manufactures high quality countersunk bolts the diameter of which ranges between 1/2″ and 1-1/2″ in most SAE, ASTM, and AASHTO specifications that include but not limited to A449, A307 Grade A and Grade 8. Countersunk bolts feature a head angle of almost 80 degrees. The head comes with or without a slot. We can create special tooling that helps produce nonstandard bolt heads and/or head dimensions with your preferred name and/or logo.

   


Standard Thread Length

Bolt lengths ≤ 6″: Thread length = (2 X diameter) + 1/4″
Bolt lengths > 6″: Thread length = (2 X diameter) + 1/2″
Note: Most stock hex bolts longer than 12″ in length will have 6″ of thread.

Countersunk Dimensions

Click table to show drawing
Bolt Diameter D F H
Body Diameter Head Diameter Head Height
Max Max Edge Sharp Min Edge Sharp Absolute Min Rounded Max Min
12 0.515 0.935 0.905 0.845 0.269 0.233
58 0.642 1.169 1.132 1.066 0.336 0.292
34 0.768 1.402 1.357 1.285 0.403 0.349
78 0.895 1.637 1.584 1.511 0.470 0.408
1 1.022 1.869 1.810 1.735 0.537 0.466
118 1.149 2.104 2.037 1.962 0.604 0.525
114 1.277 2.337 2.262 2.187 0.671 0.582
138 1.404 2.571 2.489 2.414 0.738 0.641
112 1.531 2.804 2.715 2.640 0.805 0.698

Dimensions per ASME B18.5 1990 (R 1998)